Chemo and radiation..MSKCC recommendation for HPV+

hello!

so my dad has recovered from his surgery where they wound up removing all lymph nodes on one side of neck and found verrrrryyy tiny primary tumor site at base of tongue.  PET scan before surgery showed no other cancer (didn't detect primary tumor one pet at all).  -

after a few weeks he found out the cancer was HPV positive and decided to have radiation with dr schupack at MSKCC in basking ridge (thanks for those that recommended her!).  All along the recommended course of treatment was 7 weeks of radiation daily.  Now today dad met with the head med oncologist at MSKCC and she recommends low doses of cusp Latin once a week for 7 weeks.  She thinks this will be less severe side effects.  Her thiught process is that since there is a margin, but it's small, this is a proactive measure.  She said if there was no margin, then chemo would be highly recommended.  She said dad is in more of a gray zone and this is a proactive course of action.

dads very concerned about side effects like hearing loss.  Eager to hear any advice as he wants to makes. Decision by Wednesday.  Treatment starts next week.  With the hearing loss, is that something that will come back in time or is it gone forever?  Any advice is welcome!  Thank you!